Determination of fluoroquinolones in milk, honey and water samples by salting out-assisted dispersive liquid-liquid microextraction based on deep eutectic solvent combined with MECC

Natural deep eutectic solvent-based hollow polymer inclusion membrane doped with TiO2 nanoparticles: A new design of polymer inclusion membrane for on-chip electromembrane extraction of fluoroquinolones from food samples prior to liquid chromatography tandem mass analysis

A new design of polymer inclusion membrane has been proposed with the aim of addressing issues with using common forms of liquid membranes. To do so, a natural deep eutectic solvent (NADES) was employed as an extractant in the structure of the hollow polymer inclusion membrane (HPIM). Besides polyvinyl chloride (PVC) as a base polymer, titanium dioxide nanoparticles (TiO2) as well as polyethylene glycol polymer (PEG) were incorporated into the HPIM structure to achieve a nanocomposite form with a desirable hydrophilicity. The optimal HPIM was composed of 12.5 v/w% of thymol-coumarin NADES, 3.0 w/w% of TiO2 and 40.0 v/w% of PEG based on PVC content. Aiming to compare the applicability, HPIMs with other types of extractants, such as bis(2-ethylhexyl) phthalate (DEHP), and the mixture of DEHP-NADES were also fabricated. To confirm the successful fabrication of the HPIM, containing the aforementioned extractant doped with TiO2 nanoparticles various characterization techniques were employed. The resultant HPIM was employed as a liquid membrane in an on-chip electromembrane extraction (EME) of fluoroquinolones (FQs) from various samples, followed by LC-MS/MS analysis. The parameters influencing extraction performance were analyzed, and the proposed method was validated under ideal conditions. All the samples provided excellent performance concerning limits of detection (0.01-0.08 ng mL-1), and quantification (0.03-0.25 ng mL-1) together with an excellent linearity (R2 ≥ 0.9978). The method indicates the desirable RSDs% in the range of 3.2-7.0 % (intra-day, n = 3 × 3) and 3.8-6.1 % (inter-day, n = 3 × 3) for three spiked levels. The satisfactory relative recoveries fell within the 92.0-115.0 % range.

A magnetic bead-based dual-aptamer sandwich assay for quantitative detection of ciprofloxacin using CRISPR/Cas12a

Ciprofloxacin (CIP) is a broad-spectrum fluoroquinolone antibiotic, and its excessive residues in food and water sources pose potential risks to human health. Therefore, there is a need for a rapid and convenient method for its accurate quantification. The clustered regularly interspaced short palindromic repeat (CRISPR)/Cas12a system has gained extensive application in signal detection and amplification due to the trans-cleavage activity of Cas12a. In this study, we devised a novel magnetic bead-based dual sandwich aptamer coupled with a CRISPR/Cas12a system for the precise quantification of CIP in milk, river water, and honey. Through the incorporation of a magnetic bead-based dual aptamer sandwich approach, the concentration of CIP in the samples was pre-enriched. Additionally, by optimizing the Fluorescence-Quencher (F-Q) probe concentration, detection aptamer (APTd) concentration, and assay duration, the limit of blank (LOB) of the system was determined as 362 nM, while the limit of detection (LOD) was determined as 403 nM. This enabled the accurate quantification of CIP within the linear range of 0.5 μM to 0.2 mM with high specificity. Moreover, the performance of this detection method was comparable to that of high-performance liquid chromatography (HPLC) in river water, milk, and honey samples.

Efficient voltammetric platform combining a molecularly imprinted polymer and silver-nanoparticle-decorated black phosphorus nanosheets for selective determination of Gatifloxacin

An ultrasensitive and selective voltammetric platform combined a molecularly imprinted poly(pyrrole) membrane with Ag-nanoparticle-functionalized black phosphorus nanosheets (MIP/BPNS-AgNPs) was developed for trace GAT detection. The physicochemical properties of the MIP/BPNS-AgNPs were studied by various spectroscopic and electrochemical techniques. BPNS-AgNPs improved the ambient stability and electrochemical activity of the BPNS and possessed a large surface area for accommodating abundant templates to produce specific imprinted sites. The resulting MIP/BPNS-AgNP-modified glassy carbon electrode (GCE) greatly enhanced voltammetric responses for GAT. The MIP/BPNS-AgNP/GCE exhibited admirable GAT determination performance, with two linear responses (0.001-1 and 1-50 μM), high sensitivity (9.965 and 0.5378 μA μM-1), and a low detection limit of 0.2 nM. In addition, the MIP electrode could selectively detect GAT in complex matrices and retain roust responses for a month. The applicability of MIP/BPNS-AgNP/GCE toward the detection of GAT in pharmaceutical formulations, milk, and human serum was verified with satisfactory results.

Development of QuEChERS based on the Z-Sep+and DLLME method for analysis of PBDEs in chicken eggs by GC-MS/MS

A sensitive, straightforward, and environmentally sustainable method was developed and validated for the quantification of 13 PBDEs in chicken eggs using gas chromatography coupled with triple quadrupole mass spectrometry (GC-MS/MS). The QuEChERS approach, combined with dispersive liquid-liquid microextraction (DLLME), was applied for sample preparation. Egg samples were extracted with acetonitrile and purified using Z-Sep + adsorbent. Tetrachloroethane was selected as the extraction solvent for the DLLME step. All PBDEs exhibited strong linearity, with R > 0.999 within the range of 0.20-10.0 ng/mL, and the limits of quantification (LOQ) were determined to be 10.0 pg/g. Apparent recoveries of PBDEs ranged from 85.2 % to 105.7 %. A total of 119 chicken eggs were analyzed using the developed method. BDE-47 and BDE-99 showed relatively high detection rates of 38.6 % and 24.4 %, respectively. The hazard quotient (HQ) values for BDE-47, BDE-99, and BDE-153 congeners remained well below 1.0, indicating no significant health risk from egg consumption.

Effects of Ciprofloxacin on the Production and Composition of Cellular Microcystins in Microcystis aeruginosa

Antibiotics can affect the photosynthetic system of Microcystis, potentially altering the balance of carbon and nitrogen, which may influence the synthesis of different microcystin (MC) congeners. However, the regulatory mechanisms by which antibiotics affect the synthesis of various MC congeners in Microcystis remain unknown. In this study, the effects of ciprofloxacin (CIP) on the growth, carbon and nitrogen balance, amino acid composition, mcyB gene expression, and production of different MC congeners were investigated in two toxin-producing strains of Microcystis aeruginosa. The results show that CIP exposure significantly inhibited the growth of both strains, achieving an inhibition rate of 71.75% in FACHB-315 and 41.13% in FACHB-915 at 8 μg/L CIP by the end of the cultivation. The intracellular C:N ratio in FACHB-315 increased by 51.47%, while no significant change was observed in FACHB-915. The levels of leucine, tyrosine, and arginine, as identified and quantified by UPLC-MS/MS, were significantly altered at higher CIP concentrations, leading to a reduction in leucine percentage and a notable increase in tyrosine in both strains, which contributed to a reduction in MC-LR proportion and an increase in MC-RR and MC-YR proportion. Additionally, the expression of the mcyB gene was upregulated by as much as 5.57 times, indicating that antibiotic stress could enhance MC synthesis at the genetic level, contributing to the increased toxicity of cyanobacteria. These findings emphasize the significant role of CIP in the biochemical processes of M. aeruginosa, particularly in MC synthesis and composition, providing valuable insights into the ecological risks posed by antibiotics and harmful cyanobacteria.

Recent advances and applications of ionic covalent organic frameworks in food analysis

Ionic covalent organic frameworks with both crystallinity and charged sites have attracted significant attention from the scientific community. The versatile textural structures, precisely defined channels, and abundant charged sites of ionic COFs offer immense potential in various areas such as separation, sample pretreatment, ion conduction mechanisms, sensing applications, catalytic reactions, and energy storage systems. This review presents a comprehensive overview of facile preparation methods for ionic covalent organic frameworks (iCOFs), along with their applications in food sample pretreatment techniques such as solid-phase extraction (SPE), magnetic solid-phase extraction (MSPE), and dispersive solid-phase extraction (DSPE). Furthermore, it highlights the extensive utilization of iCOFs in detecting various food contaminants including pesticides, contaminants from food packaging, veterinary drugs, perfluoroalkyl substances, and poly-fluoroalkyl substances. Specifically, this review critically discusses the limitations, challenges, and future prospects associated with employing iCOF materials to ensure food safety.

On-site extraction using a 3D printed device coated with Zn/Co-ZIF-derived carbon followed by an on-line SIA-HPLC-FL system for fluoroquinolones determination in wastewater

A 3D printed device covered with Zn/Co-ZIF-derived carbon allows the on-site extraction of fluoroquinolones (FQs) from wastewater, avoiding the sample transportation to the laboratory, and the subsequent elution, separation and determination using an on-line flow system based on sequential injection analysis (SIA) coupled to HPLC-FL. Several parameters that affect the extraction efficiency and desorption were optimized including the sorption phase immobilization technique on the 3D device, extraction time, pH effect, sample volume as well as the type of eluent, eluent volume, and flow rate. Under optimum conditions, detection limits of 3-9 ng L-1 were achieved for norfloxacin, ciprofloxacin, danofloxacin, enrofloxacin and difloxacin. The precision expressed as relative standard deviation (%RSD, n = 3), showed intraday and interday ranges of 1.5-5.3% and 2.8-5.7%, respectively, demonstrating a good precision of the proposed methodology. To assess matrix effects and accuracy of the proposed method in real samples, recovery studies were performed without and with FQs spiked at different concentrations (0.5-10 μg L-1) to wastewater samples, showing good recoveries in the range of 91-104%. The results allow to confirm the applicability of MOF-derived carbons as adsorbents for on-site extraction, and the satisfactory separation and quantification of FQs by a SIA-HPLC-FL on-line system after their desorption with small eluent volumes.

Molecularly imprinted solid-phase extraction combined with non-ionic hydrophobic deep eutectic solvents dispersed liquid-liquid microextraction for efficient enrichment and determination of the estrogens in serum samples

Hormonal drugs in biological samples are usually in low concentration and highly intrusive. It is of great significance to enhance the sensitivity and specificity of the detection process of hormone drugs in biological samples by utilizing appropriate sample pretreatment methods for the detection of hormone drugs. In this study, a sample pretreatment method was developed to effectively enrich estrogens in serum samples by combining molecularly imprinted solid-phase extraction, which has high specificity, and non-ionic hydrophobic deep eutectic solvent-dispersive liquid-liquid microextraction, which has a high enrichment ability. The theoretical basis for the effective enrichment of estrogens by non-ionic hydrophobic deep eutectic solvent was also computed by simulation. The results showed that the combination of molecularly imprinted solid-phase extraction and deep eutectic solvent-dispersive liquid-liquid microextraction could improve the sensitivity of HPLC by 33∼125 folds, and at the same time effectively reduce the interference. In addition, the non-ionic hydrophobic deep eutectic solvent has a relatively low solvation energy for estrogen and possesses a surface charge similar to that of estrogen, and thus can effectively enrich estrogen. The study provides ideas and methods for the extraction and determination of low-concentration drugs in biological samples and also provides a theoretical basis for the application of non-ionic hydrophobic deep eutectic solvent extraction.

Graphene oxide mediated CdSe quantum dots fluorescent aptasensor for high sensitivity detection of fluoroquinolones

In view of the urgent need for fluoroquinolones contamination detection in the fields of food safety, a novel aptasensor based on the fluorescence quenching property of graphene oxide (GO) and the fluorescence characteristic of cadmium selenide quantum dots (CdSe QDs) was developed for fluoroquinolones highly sensitive detection in this work. The CdSe QDs with carboxyl-rich surface were synthesized successfully and fluoresced at 525 nm under the optimal excitation light of 366 nm. Based on the hydrophobic and π-π stacking between GO and aptamer, aptamer labeled by CdSe QDs fluorescence (CdSe QDs-apt) were adsorbed by GO and the fluorescence of CdSe QDs was quenched. After the aptamer combined specifically with fluoroquinolones, greater specific force lead to the desorption of CdSe QDs-apt from GO and fluorescence recovery. Represented by Ciprofloxacin (CIP), a member of fluoroquinolones, the fluorescence emission increased with the increasing of CIP concentrations from 8 nM to 500 nM, and the detection limit was 0.42 nM. The spiked recoveries in real samples of honey and milk were 91.5-96.9 % and 90.3-95.2 %, respectively, indicating that the aptasensor was reliable. Moreover, the fluorescence responses of multiple members of fluoroquinolones were found to be consistent, denoting that the fluorescence aptasensor can be used to detect the total amount of multiple members of fluoroquinolones. These results showed that the aptasensor can be used as a promising platform for fluoroquinolones detection.

Determination of trace fluoroquinolones in honey and milk based on cyclodextrin modified magnetic metal-organic frameworks solid phase extraction coupled with ultra-high performance liquid chromatography

Long-term intake of animal-derived foods with excessive fluoroquinolones (FQs) will cause damage to human health, so it is critical to establish a feasible approach for sensitive and rapid monitoring of FQs residues. In this study, a new cyclodextrin modified magnetic metal-organic frameworks (Fe3O4@UiO-66-CD) was successfully synthesized by amidation reaction and applied to magnetic solid phase extraction (MSPE) for FQs analysis. The adsorption behavior of Fe3O4@UiO-66-CD was consistent with the pseudo-second-order kinetics and Freundlich isothermal adsorption model, which indicated that the designed material had various interactions on FQs, such as host-guest interaction and π-π interaction. The parameters of MSPE were optimized and the determination method of norfloxacin, enrofloxacin, lomefloxacin and gatifloxacin was established by using MSPE combined with ultra-high performance liquid chromatography (UHPLC) and fluorescence detector (FLD). The method validation results displayed that the detection limits were 0.02-0.09 ng/mL, and the RSDs of intra-day and inter-day precision were less than 4.1 and 6.4 %, respectively. In the target FQs analysis of real honey and milk samples, the recoveries at different fortified concentrations were in the ranges of 88.4 % to 108.6 % with RSD ≤ 5.7 %. The results showed that the proposed method was sensitive, accurate and reliable for the determination of trace FQs in animal-derived foods.

Current analytical strategies for the determination of quinolone residues in milk

Quinolones are potent antibacterial drugs extensively utilized for treating bacterial infections in poultry. However, the presence of quinolone antibiotic residues in milk is a matter of concern due to potential health risks and adverse effects on milk quality. This review provides an overview of current analytical strategies for the determination of quinolone residues in milk. Various sample preparation techniques, such as liquid-phase extraction, solid-phase extraction and QuEChERS, are discussed, along with detection methods including instrument-based detection, immune-based detection, and microbial detection. The advantages and limitations of each method are highlighted, as well as their applicability in different stages of milk production. Additionally, recent advancements in sample preparation and detection methods are presented. This comprehensive review aims to contribute to the development of accurate and reliable methods for the detection of quinolone residues in milk, ensuring the safety and quality of dairy products.

Subzero-temperature homogeneous liquid-liquid extraction for the stereoselective determination of chiral triadimefon and its metabolite in water, fruit juice, vinegar, and fermented liquor by HPLC

A novel method based on homogeneous liquid-liquid extraction with deep eutectic solvents (DES) under subzero-temperature conditions in combination with high performance liquid chromatography (HPLC) for the determination of chiral fungicide triadimefon (TF) and its metabolite triadimenol (TN) in water, fruit juice, vinegar, and fermented liquor was developed in this study. The method involved using deep eutectic solvents (DES) under subzero-temperature conditions in combination with high performance liquid chromatography (HPLC). This novel technique, known as subzero-temperature homogeneous liquid-liquid extraction (STHLLE), offers several advantages, including high efficiency, time-saving, low-cost, and eco-friendliness. The enantiomers of chiral TF and TN were simultaneously separated and quantified using HPLC coupled with a Daicel Chiralpak OD-RH column. Various experimental parameters such as DES composition and volume, freezing condition, salt concentration, and pH were optimized to enhance the recoveries of the target analytes. Under the optimized conditions, spiked recoveries of six enantiomers (i.e., S-TF, R-TF, SR-TN, RS-TN, SS-TN, and RR-TN) in the water, fruit juice, vinegar, and fermented liquor samples were 82.2-100.1% with relative standard deviations of 0.4-10.1%. The current method demonstrated a detection range of 0.03-0.06 mg L-1 in the target analytes. This established technique exhibits potential for efficient and precise extraction and quantification of the enantiomers of TF and TN in water phase samples.

Surface imprinted-covalent organic frameworks for efficient solid-phase extraction of fluoroquinolones in food samples

Molecularly imprinting on covalent organic frameworks (MI-COF) is a promising way to prepare selective adsorbents for effective extraction of fluoroquinolones (FQs). However, the unstable framework structure and complex imprinting process are challenging for the construction of MI-COF. Here, we report a facile surface imprinting approach with dopamine to generate imprinted cavities on the surface of irreversible COF for highly efficient extraction of FQs in food samples. The irreversible-linked COF was fabricated from hexahydroxytriphenylene and tetrafluorophthalonitrile to ensure COF stability. Moreover, the introduction of dopamine surface imprinted polymer into COF provides abundant imprinted sites and endows excellent selectivity for FQs recognition against other antibiotics. Taking enrofloxacin as a template molecule, the prepared MI-COF gave an exceptional adsorption capacity of 581 mg g-1, a 2.2-fold enhancement of adsorption capacity compared with nonimprinted COF. The MI-COF was further explored as adsorbent to develop a novel solid-phase extraction method coupled with high-performance liquid chromatography for the simultaneous determination of enrofloxacin, norfloxacin and ciprofloxacin. The developed method gave the low limits of detection at 0.003-0.05 ng mL-1, high precision with relative standard deviations less than 3.5%. The recoveries of spiked FQs in food samples ranged from 80.4% to 110.7%.

Quantitative determination of bromochloroacetamide in mice urine by gas chromatography combined with salting-out assisted dispersive liquid-liquid microextraction

Bromochloroacetamide (BCAcAm) is the main haloacetamide (HAcAm) detected in drinking water in different regions and exhibits strong cytotoxicity and genotoxicity. However, there is no appropriate method for detecting BCAcAm in urine or other biological samples, and thus, the internal exposure level in the population cannot be accurately assessed. In this study, a gas chromatography-electron capture detector (GC-ECD) was combined with salting-out assisted dispersive liquid-liquid microextraction (SA-DLLME) to develop a rapid and robust method for BCAcAm detection in urine of mice continuously exposed to BCAcAm. The factors influencing the pre-treatment procedure, including the type and volume of extraction and disperser solvents, extraction and standing time, and the amount of salt, were evaluated systematically. Under the optimised conditions, the analyte achieved good linearity in the spiked concentration range of 1.00-400.00 μg L^-1, and the correlation coefficient was higher than 0.999. The limit of detection (LOD) and the limit of quantification (LOQ) were 0.17 μg L^-1 and 0.50 μg L^-1, respectively. The recoveries ranged from 84.20% to 92.17%. The detection of BCAcAm at three different calibration levels using this method afforded an intra-day precision of 1.95-4.29%, while the inter-day precision range was 5.54-9.82% (n = 6). This method has been successfully applied to monitor the concentration of BCAcAm in mouse urine in toxicity experiments and can provide technical support for assessing human internal exposure levels and health risks in later studies.

Preparation of a hydrophobic deep eutectic solvent and its application in the detection of quinolone residues in cattle urine

Enrichment for the detection of quinolone residues is usually cumbersome and requires large amounts of toxic organic reagents. Therefore, this study synthesized a low-toxicity hydrophobic deep eutectic solvent (DES) with DL-menthol and p-cresol, which was then characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance, and thermal analysis. A simple and rapid vortex-assisted liquid-liquid microextraction method was developed based on this DES for the extraction of eight quinolones from cattle urine. The optimal extraction conditions were screened by examining the DES volume, extraction temperature, vortex time, and salt concentration. Under the optimal conditions, the linear ranges of the eight quinolones were 1 ~ 100 μg/L with good linearity (r² was 0.998 ~ 0.999), and the limits of detection and quantification were 0.08 ~ 0.30 μg/L and 0.27 ~ 0.98 μg/L, respectively. The average extraction recoveries of spiked cattle urine samples were 70.13 ~ 98.50% with relative standard deviations below 13.97%. This method can provide a reference for the pre-treatment of quinolone residue detection.

Rapid microwave synthesis of MOF microrods: Dispersive SPE coupled with UHPLC-MS/MS to determine fluoroquinolones in honey

A novel sorbent Cu-S metal-organic framework (MOF) microrods was prepared for dispersive solid-phase extraction via microwave synthesis and used to determine 12 fluoroquinolones (FQs) in honey samples employing ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The best extraction efficiency was achieved by optimizing sample pH, sorbent quantity, eluent type/volume, and extraction and elution time. The proposed MOF exhibits advantages such as rapid synthesis time (20 min) and outstanding adsorption ability toward zwitterionic FQs. These advantages can be attributed to multiple interactions, including hydrogen bonding, π-π interaction, and hydrophobic interaction. The limits of detection of analytes were 0.005-0.045 ng g^-1. Acceptable recoveries (79.3%-95.6%) were obtained under the optimal conditions. Precision (relative standard deviation, RSD) was <9.2%. These results demonstrate the utility of our sample preparation method and the high capacity of Cu-S MOF microrods for rapid and selective extraction of FQs from honey samples.

A new application of continuous sample drop flow microextraction using octanoic acid as a green extraction solvent for the determination of antibiotic drugs in urine samples

In this study, octanoic acid (OA) was used as an extraction solvent for the pre-concentration and determination of three antibiotic drugs (levofloxacin, metronidazole, and tinidazole) in urine samples. To extract the antibiotic drugs, a green solvent was used as the extraction solvent in the continuous sample drop flow microextraction method, followed by a high-performance liquid chromatography photodiode array detector. According to the findings, the present study offers an environmentally friendly analytical method with a high capacity for the microextraction of the antibiotic drugs at very low concentrations. The calculated detection limits were 6.0-10.0 µg/L and the linear range was found between 20 and 780 µg/L. The proposed method showed excellent repeatability with the RSD values ranging from 2.8 to 5.5%. The relative recoveries were between 79.0 and 92.0% in the urine samples with spiked levels of 40.0-100.0 µg/L for metronidazole and tinidazole, and 100.0-200.0 μg/L for levofloxacin.

Pharmacokinetics, withdrawal time, and dietary risk assessment of enrofloxacin and its metabolite ciprofloxacin, and sulfachloropyridazine-trimethoprim in Taihe black-boned silky fowls

Enrofloxacin (ENR) and sulfachloropyridazine combined with trimethoprim (TMP) were commonly used in poultries to treat bacterial infections. In this study, the pharmacokinetics of these antibiotics in four tissues of Taihe black-boned silky fowls was studied. The results showed that these drugs were absorbed and distributed rapidly, with the highest concentration showing in skin. Meanwhile, ENR and its metabolite ciprofloxacin (CIP) and TMP were depleted slowly, particularly in skin with the elimination half-lives being 37.1, 36.9, and 72.7 days, respectively. It may be attributed to the abundance of melanin in skin. The dietary risk assessment suggested that the long-term dietary intakes of ENR, CIP, and TMP showed a considerable threat to human health. Based on the experiment, the withdrawal times of 284 days for ENR + CIP and 159 days for TMP were acquired, which showed that these drugs are not appropriate for the application in Taihe black-boned silky fowls.

Recent advances and applications of magnetic covalent organic frameworks in food analysis

Recently, covalent organic frameworks (COFs) have been widely used to prepare magnetic adsorbents for food analysis due to their highly tunable porosity, large specific surface area, excellent chemical and thermal stability and large delocalised π-electron system. This review summarises the main types and preparation methods of magnetic COFs and their applications in food analysis for the detection of pesticide residues, veterinary drugs, endocrine-disrupting phenols and estrogens, plasticisers and other food contaminants. Furthermore, challenges and future outlook in the development of magnetic COFs for food analysis are discussed.

Determination of quinolone antibiotics in honey by pH-induced natural deep eutectic solvent combined with vortex-assisted dispersive liquid-liquid microextraction

A green, fast, and efficient pH-induced natural deep eutectic solvent combined with vortex-assisted dispersive liquid-liquid microextraction method (pH-NADES-VA-DLLME) followed by HPLC was established for determination of ofloxacin (OFL), ciprofloxacin (CIP) and enrofloxacin (ENR) in honey. In this method, NaOH, as an emulsifier, can increase the contact area between the NADES and the sample solution, which can efficiently improve the extraction efficiency of the analytes. Moreover, HCl acts as the phase separation agent without centrifugation in the process, which can greatly enhance the efficiency of the sample analysis process. In addition, the main factors affecting the extraction effect were optimized by single factor experiments. Under the optimal conditions, the limits of detection (LODs), the limits of quantification (LOQs) and recoveries were in the range of 0.004-0.015 μg mL^-1, 0.012-0.050 μg mL^-1, and 98.0-112.5%, respectively. The RSD values of intra-day and inter-day precisions were no more than 5.5% and 6.0%, respectively. The developed method was successfully applied to determine the three quinolone antibiotics in honey.

Development of β-cyclodextrin crosslinked citric acid encapsulated in polypropylene membrane protected-μ-solid-phase extraction device for enhancing the separation and preconcentration of endocrine disruptor compounds

Endocrine disruptor compounds (EDCs) such as plasticisers, surfactants, pharmaceutical products, personal care products and pesticides are frequently released into the environmental waters. Therefore, a sensitive and environmentally friendly method is entailed to quantify these compounds at their trace level concentrations. This study encapsulated the β-cyclodextrin crosslinked with citric acid in a polypropylene membrane protected-μ-solid phase extraction (BCD-CA μ-SPE) device for preconcentrating the EDCs (triclosan, triclocarban, 2-phenylphenol, 4-tert-octylphenols and bisphenol A) in real water samples before the analysis by high-performance liquid chromatography. FT-IR and TGA results indicated that BCD-CA was successfully synthesised with the formation of ester linkage (1078.33 cm^-1) and O-H stretching from carboxylic acid (3434.70 cm^-1) with higher thermal stability as compared with native CD with the remaining weight above 72.1% at 500 °C. Several critical parameters such as the sorbent loading, type and amount of salts, extraction time, sample volume, sample pH, type and volume of desorption solvents and desorption time were sequentially optimised and statistically validated. Under the optimum condition, the use of BCD-CA μ-SPE device had manifested good linearity (0.5-500 μg L^-1) with the determination of the coefficient range of 0.9807-0.9979. The p-values for the F-test and t-test (6.60 × 10^-8 - 1.77 × 10^-5) were lesser than 0.05 and low detection limits ranging from 0.27 to 0.84 μg L^-1 for all studied EDCs. The developed technique was also successfully applied for EDC analyses in four distinct real water samples, namely, wastewater, river water, tap water and mineral water, with good EDCs recoveries (80.2%-99.9%), low relative standard deviations (0.1%-3.8%, n = 3) with enrichment factor ranging from 9 to 82 folds. These results signified the potential of the BCD-CA μ-SPE device as an efficient, sensitive, and environmentally friendly approach for analyzing EDCs.

A novel terbium (III) and aptamer-based probe for label-free detection of three fluoroquinolones in honey and water samples

Fluoroquinolones, a family of synthetic broad-spectrum antibiotics, are widely used in clinical medicine, farm animals and aquaculture. Residues of fluoroquinolones in samples have attracted much attention because of growing food safety and public health concerns. Here, a novel Tb³⁺ ion-enrofloxacin aptamer coordination probe was prepared to develop a sensitive and rapid label-free fluorescence assay for specific detection three fluoroquinolones. In presence of the target, Tb³⁺ ion- enrofloxacin aptamer probe specifically bound with enrofloxacin, norfloxacin and ciprofloxacin, leading to a sharp increase in fluorescence emission of the probe. Under the optimized conditions, fluorescence increased linearly in the 1.0-100.0 ng/mL range for the three fluoroquinolones, with 0.053 ng/mL limit of detection for ciprofloxacin, 0.020 ng/mL limit of detection for norfloxacin and 0.061 ng/mL limit of detection for enrofloxacin. Satisfactory recovery (80.10-102.48%) in spiked honey and water samples were obtained for the three fluoroquinolones with relative standard deviations between 0.21% and 5.44% (n = 3).

A magnetic ionic liquid based vortex-assisted dispersive liquid-liquid microextraction coupled with back-extraction for the enrichment of fluoroquinolone antibiotics

In the present work, a magnetic ionic liquid (MIL) ([Co(DMBG)₂][Co(hfaca)₃]) was designed and synthesized with both the cation and anion respectively containing a paramagnetic component. With the prepared MIL as the extraction solvent, a vortex-assisted dispersive liquid-liquid microextraction (VA-DLLME) method was developed and combined with back-extraction for the enrichment of five fluoroquinolone antibiotics (FQs). The MIL can be easily collected and separated from the aqueous phase under an external magnetic field due to the strong magnetic susceptibility and red color. Some experimental factors affecting the extraction efficiency were investigated, and the optimum extraction efficiency was obtained in a basic solution (pH=9) for the extraction process and with 2% (v/v) formic acid as the back-extraction solvent. Under the optimized extraction and back-extraction conditions, the proposed method was validated and exhibited good linearity with coefficients of determination (R²) above 0.9956 in the range of 2.5-800 ng·mL^-1 and 5.0-800 ng·mL^-1, low limits of detection (LODs) within 0.75-1.5 ng·mL^-1 and satisfactory intra-day and inter-day precisions with relative standard deviations (RSDs) respectively less than 10.6% and 8.6%. Finally, the method was applied for the determination of five FQs in four samples of tap water, milk, honey and chicken, and good precision with RSDs of 0.5-9.5% and acceptable recoveries (73.8-114.3%) were obtained.

Simultaneous determination of the four key fluoroquinolones and two antipsychotics in fish and shrimp by LC-MS/MS

In this study, we developed and validated a liquid chromatography triple quadrupole tandem mass spectrometry (LC-MS/MS) method used to simultaneously determine levels of four fluoroquinolones (ofloxacin, norfloxacin, lomefloxacin, and pefloxacin) and two antipsychotics (diazepam and methaqualone) in fish and shrimp. The samples were extracted with a mixture of anhydrous sodium sulfate and acetonitrile, and purified by C₁₈ cartridge solid-phase extraction with an optimized eluent. The MS² method was applied to recognize the molecular structure of these compounds according to a main fragmentation scheme. The key ions of identification and quantification were deduced from chemical structures. Multiple reaction monitoring was used to quantitatively analyse the compounds of interest. Satisfactory linearities were obtained (R² ≥0.99) with the limits of quantitation (LOQs) ranging between 0.03 and 1.96 μg kg^-1. The recoveries were 74-122%, with a relative standard deviation (RSD) below 4.9% for these compounds at the spiking level of three, five, and ten times the LODs, respectively. The LC-MS/MS method allows precise and sensitive determination of residues of six important banned veterinary drugs in fish and shrimp tissue. This methodological approach solved the problem imposed by the need for two or more analysis methods to analyse the compounds of interest described in this study.

Applications of capillary electrophoresis in the fields of environmental, pharmaceutical, clinical and food analysis (2019-2021)

So far, the potential of capillary electrophoresis (CE) in the application fields has been increasingly excavated due to the advantages of simple operation, short analysis time, high-resolution, less sample consumption and low cost. This review examines the implementations and advancements of CE in different application fields (environmental, pharmaceutical, clinical and food analysis) covering the literature from 2019 to 2021. In addition, ultrasmall sample injection volume (nanoliter range) and short optical path lead to relatively low concentration sensitivity of the most frequently used UV-absorption spectrophotometric detection, so the pretreatment technology being developed has been gradually utilized to overcome this problem. Despite the review is focused on the development of CE in the fields of environmental, pharmaceutical, clinical and food analysis, the new sample pretreatment techniques of microextraction and enrichment which fit excellently to CE in recent three years are also described briefly. This article is protected by copyright. All rights reserved.

Miniaturized green sample preparation approaches for pharmaceutical analysis

The development of green sample preparation procedures is an extremely important research field in which more and more applications are constantly being proposed in different areas, including pharmaceutical analysis. This review article is aimed at providing a general overview of the development of miniaturized green analytical sample preparation procedures in the pharmaceutical analysis field, with special focus on the works published between January 2017 and July 2021. Particular attention has been paid to the application of environmentally friendly solvents and sorbents as well as nanomaterials or high extraction capacity sorbents in which the solvent volumes and reagents amounts are drastically reduced, with their subsequent advantages from the sustainability point of view.

In-situ formation/decomposition of deep eutectic solvent during solidification of floating organic droplet-liquid-liquid microextraction method for the extraction of some antibiotics from honey prior to high performance liquid chromatography-tandem mass spectrometry

A new liquid-liquid microextraction approach by applying a deep eutectic solvent was adopted for the extraction of four antibiotics (penicillin G, dihydrostreptomycin, enrofloxacin, and ciprofloxacin) from honey samples. The enriched analytes were analyzed by HPLC-MS/MS. The procedure was carried out by synthesis of tetrabutylammonium chloride: p-cresol deep eutectic solvent in the sample solution and then its decomposition in the presence of an acid. In-solution formation of deep eutectic solvent provided wide contact areas among the extractant and sample solution, and accelerated sample preparation. Also, its decomposition enabled collection of the final extraction phase without centrifugation. Low LODs (0.55-0.79 ng/g) and LOQs (1.9-2.6 ng/g), high ERs (70-92%), and suitable RSDs (≤ 6.9%) were obtained. After performing the method on real samples, dihydrostreptomycin was found in several honey samples.

Simultaneous Determination of Ciprofloxacin and Ofloxacin in Animal Tissues with the Use of Capillary Electrophoresis with Transient Pseudo-Isotachophoresis

We have developed a precise and accurate method for the determination of ciprofloxacin and ofloxacin in meat tissues. Our method utilizes capillary electrophoresis with a transient pseudo-isotachophoresis mechanism and liquid–liquid extraction during sample preparation. For our experiment, a meat tissue sample was homogenized in pH 7.00 phosphate buffer at a ratio of 1:10 (tissue mass: buffer volume; g/mL). The extraction of each sample was carried out twice for 15 min with 600 µL of a mixture of dichloromethane and acetonitrile at a 2:1 volume ratio. We then conducted the electrophoretic separation at a voltage of 16 kV and a temperature of 25 °C using a background electrolyte of 0.1 mol/L phosphate–borate (pH 8.40). We used the UV detection at 288 nm. The experimentally determined LOQs for ciprofloxacin and ofloxacin were 0.27 ppm (0.8 nmol/g tissue) and 0.11 ppm (0.3 nmol/g tissue), respectively. The calibration curves exhibited linearity over the tested concentration range of 2 to 10 nmol/g tissue for both analytes. The relative standard deviation of the determination did not exceed 15%, and the recovery was in the range of 85–115%. We used the method to analyze various meat tissues for their ciprofloxacin and ofloxacin contents.

Deep Eutectic Solvents Application in Food Analysis

Current trends in Analytical Chemistry are focused on the development of more sustainable and environmentally friendly procedures. However, and despite technological advances at the instrumental level having played a very important role in the greenness of the new methods, there is still work to be done regarding the sample preparation stage. In this sense, the implementation of new materials and solvents has been a great step towards the development of "greener" analytical methodologies. In particular, the application of deep eutectic solvents (DESs) has aroused great interest in recent years in this regard, as a consequence of their excellent physicochemical properties, general low toxicity, and high biodegradability if they are compared with classical organic solvents. Furthermore, the inclusion of DESs based on natural products (natural DESs, NADESs) has led to a notable increase in the popularity of this new generation of solvents in extraction techniques. This review article focuses on providing an overview of the applications and limitations of DESs in solvent-based extraction techniques for food analysis, paying especial attention to their hydrophobic or hydrophilic nature, which is one of the main factors affecting the extraction procedure, becoming even more important when such complex matrices are studied.

Synthesis of molecularly imprinted polymers for extraction of fluoroquinolones in environmental, food and biological samples

In recent years, fluoroquinolones have been found present in important water resources and food sources which compromises the food quality and availability, thereby, causing risks to the consumer. Despite the recent advancement in the development of analytical instrumentation for routine monitoring of fluoroquinolones in water, food, and biological samples, sample pre-treatment is still a major bottleneck of the analytical methods. Therefore, fast, selective, sensitive, and cost-effective sample preparation methods prior to instrumental analysis for fluoroquinolones residues in environmental, food and biological samples are increasingly important. Solid-phase extraction using different adsorbents is one of the most widely used pre-concentration/clean-up techniques for analysis of fluoroquinolones. Molecularly imprinted polymers (MIPs) serve as excellent effective adsorbent materials for selective extraction, separation, clean-up and preconcentration of various pollutants in different complex matrices. Therefore, synthesis of MIPs remains crucial for their applications in sample preparation as this offers much-needed selectivity in the extraction of compounds in complex samples. In this study, the progress made in the synthesis of MIPs for fluoroquinolones and their applications in water, food and biological samples were reviewed. The present review discusses the selection of all the elements of molecular imprinting for fluoroquinolones, polymerization processes and molecular recognition mechanisms. In conclusion, the related challenges and gaps are given to offer ideas for future research focussing on MIPs for fluoroquinolones.

[Annual review of capillary electrophoresis technology in 2020]

该文为2020年毛细管电泳(capillary electrophoresis, CE)技术年度回顾。归纳总结了以“capillary electrophoresis-mass spectrometry”或“capillary isoelectric focusing”或“micellar electrokinetic chromatography”或“capillary electrophoresis”为关键词在ISI Web of Science数据库中进行主题检索得到的2020年CE技术相关研究论文222篇,以及中文期刊《分析化学》和《色谱》中CE技术相关的研究论文37篇。对2020年影响因子(IF)≥5.0的Analytical Chemistry, Food Chemistry, Analytica Chimica Acta和Talanta等13本期刊的38篇文章报道的科研工作作了逐一介绍;对IF<5.0的期刊中CE技术报道较为集中的Journal of Chromatography A和Electrophoresis两本分析化学类期刊发表40篇文章中的代表性内容作了综合介绍;对重要的中文期刊《分析化学》出版的“核酸适配体专刊”和《色谱》出版的2期CE技术专刊所收录的37篇文章中的工作作了总体介绍。总体来说,2020年CE技术发展趋势仍以毛细管电泳-质谱(CE-MS)的新方法和新应用最为突出,主要集中在CE-MS与电化学检测、固相萃取以及多种毛细管电泳模式的联用方面,CE-MS接口相关的报道较前几年有所减少;常规CE技术则以胶束电动毛细管色谱(MEKC)在复杂样本分析、浓缩富集应用为主,尤其在食品和药品等复杂基质样本分析方面的报道较为集中;此外,我国CE相关领域专家学者的科研成果涵盖了CE在生命科学、临床医学、医药研发、环境科学、天然产物、食品分析等领域的应用,代表了国内CE科研应用水平和现状。

Hydrophilic deep eutectic solvents modified phenolic resin as tailored adsorbent for the extraction and determination of levofloxacin and ciprofloxacin from milk

A reliable and efficient method for the simultaneous extraction and determination of antibiotics of ciprofloxacin and levofloxacin from milk was developed with solid phase extraction based on tailored adsorbent materials of deep eutectic solvents modified phenolic resin (DES-R-SPE). Six types of polyhydric alcohol-based hydrophilic DESs were prepared to modify the phenolic resin with the compositions of 3-aminophenol as a functional monomer, glyoxylic acid as a crosslinker, and polyethylene glycol 6000 as a porogen. And the prepared DES-Rs showed better extraction capacities for the target analytes than the unmodified phenolic resin because of more hydrogen bonding and electrostatic interactions supplied by DESs. The choline chloride-glycerol-based resin (DES¹-R) with the highest adsorption amounts was selected and the adsorption behavior of it was studied with static adsorption and the dynamic adsorption performance; the adsorption process followed Freundlich isotherm (R² ≥ 0.9337) and pseudo-second-order (R² ≥ 0.9951). The present DES¹-R-SPE method showed good linear range from 0.5 to100 μg mL^-1 (R² ≥ 0.9998), good recoveries of spiked milk samples (LEV, 96.7%; CIP, 101.5%), and satisfied repeatability for intra-day and inter-day (LEV, RSD≤5.4%; CIP, RSD≤4.6%).

Vortex assisted liquid-liquid microextraction based on in situ formation of a natural deep eutectic solvent by microwave irradiation for the determination of beta-blockers in water samples

In this study, a simple, green, and reliable method combining vortex-assisted liquid-liquid microextraction based on in situ formation of a novel hydrophobic natural deep eutectic solvent (NADES-VA-LLME) and high-performance liquid chromatography (HPLC) was developed for the determination of metoprolol and propranolol in water samples. The novel NADES was synthesized in situ within only 20 s by subjecting the water sample containing azelaic acid and thymol to microwave irradiation at 50 ˚C. Initial studies indicated that a 17:1 ratio of thymol to azelaic acid yielded the highest response for analytes. The influence of 7 parameters, including NADES volume, salt amount, sample pH, vortex time, centrifugation time, microwave time, and temperature, were screened using a 2^7-3 fractional factorial design. The obtained significant parameters were optimized by response surface methodology employing a Box-Behnken design. The method displayed satisfactory linearity (r=0.9996) for metoprolol and propranolol with limits of detection of 0.2 and 0.1 µg/L, respectively. The relative standard deviation at 2.5, 40, and 80 µg/L levels was lower than 6%, with accuracy in the range of 90.8-100.2%. Enrichment factors were 147.0 and 144.4 for metoprolol and propranolol, respectively. This study demonstrates that the developed in situ NADES-VA-LLME-HPLC technique can be considered as a fast and environmentally friendly alternative for isolation/preconcentration of β-blockers from water samples.

Deep eutectic solvent assisted synthesis of carbon dots using Sophora flavescens Aiton modified with polyethyleneimine: Application in myricetin sensing and cell imaging

Here, an efficient method for synthesizing carbon dots (CDs) using a deep eutectic solvent (DES) was developed. To investigate the influence of different DESs on the quantum yield of CDs, different hydrogen-bonding acceptors (HBAs) and hydrogen-bonding donors (HBDs) were used to synthesize the DES and prepare CDs. Using Sophora flavescens Aiton as precursor, CDs were prepared using choline chloride (ChCl)/urea based DES as reaction media and doping agent in the presence of water. The CDs showed strong blue fluorescence and were further modified with polyethyleneimine (CDs@PEI). The fluorescence intensity of CDs@PEI was selectively quenched by myricetin with a limit of detection (LOD) of 10 nM. Furthermore, CDs@PEI was used to analyze myricetin in the extracts that were fluorescent by DES with satisfactory performance of Abelmoschus manihot (Linn.) Medicus flowers, vine teas and blueberries. Finally, the bio-imaging application of CDs@PEI was tested and the results confirmed its potential application in bio-imaging.